A major focus of this project has been improving the accuracy of interpretation of spine MR and CT by precise anatomic correlations. Progress toward the first objective, a systematic correlation of MR and CT images with sections has been documented in 40 journal articles describing correlations of high resolution axial, coronal and sagittal MR images with cryomicrotomic sections. Important progress has been made toward the second objective: to study the CT and MR appearance of normal developmental and degenerative changes within the spine. The most noteworthy and original observations, on the internal structure of the intervertebral disc visualized with MR, have been reported in a series of papers. These studies have suggested that normal disc degeneration is characterized by gradual increase in collagen in the nucleus and anulus and that degeneration is characterized by a radial tear of the anulus fibrosus, which leads to disc bulging, disc space collapse, or nucleus pulposus herniation. These findings need more study. The third objective, to study changes in spine anatomic relationships as the spine is flexed, extended or loaded, has produced observations in changes in neural foramina, discs, spinal canal as the spine is subjected to various loads. This work will be continued to identify the characteristics of motion segments (intervertebral discs) in which axial loading produces the greatest change in disc or foramen dimension, or produces more compression. Support is requested to continue work that improves the diagnostic value of CT and MR and to study the provocative findings of the first grant period. The new focus of the project is acute degenerative changes in the intervertebral disc including the radial tear of the anulus, herniation of the nucleus pulposus. Cadavers in the 1-49 year age group will be studied. The techniques of cryomicrotomy and MR will also be applied to acute intervertebral disc degeneration, which has been modelled in dogs, by means of a nucleotome. More precise interpretation of CT and MR studies, improved radiographic detection of nerve compression, and betters election of patients for conventional and innovative treatments can be anticipated.